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Updated: Aug 9, 2026
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Extracting the Cochlea from a Human Temporal Bone: A Cadaveric Protocol
Published on: August 18, 2023
Cochlear Structure in the Dolphin, Lagenorhynchus obliquidens
E G Wever1, J G McCormick, J Palin
1Auditory Research Laboratories, Princeton University, Princeton, New Jersey 08540.
Summary
This study counted hair and ganglion cells in Pacific white-sided dolphin cochleas. Researchers found over 16,000 hair cells and 50,000 ganglion cells, offering insights into dolphin auditory systems.
Area of Science:
- Marine Mammal Biology
- Auditory Neuroscience
- Comparative Anatomy
Background:
- Understanding the auditory system of marine mammals is crucial for conservation and bioacoustics.
- The Pacific white-sided dolphin (Lagenorhynchus obliquidens) is a key species in North Pacific ecosystems.
Purpose of the Study:
- To quantify the number and distribution of inner and outer hair cells.
- To estimate the total population of spiral ganglion cells in the cochlea of Lagenorhynchus obliquidens.
Main Methods:
- Histological analysis of five intravital perfusion-fixed cochleas.
- Celloidin embedding and serial sectioning.
- Microscopic counting and estimation of hair cells and ganglion cells, with correction for sectioning artifacts.
Main Results:
- An estimated 3,272 inner hair cells and 12,899 outer hair cells were identified.
- A total of approximately 16,171 hair cells were calculated.
- The spiral ganglion cell population was estimated at 50,412 cells.
Conclusions:
- The study provides precise cell counts for the dolphin cochlea, contributing to the understanding of cetacean auditory capabilities.
- These quantitative data are essential for future research on dolphin hearing and sound processing.
Related Concept Videos
01:13The Cochlea
The cochlea is a coiled structure in the inner ear that contains hair cells—the sensory receptors of the auditory system. Sound waves are transmitted to the cochlea by small bones attached to the eardrum called the ossicles, which vibrate the oval window that leads to the inner ear. This causes fluid in the chambers of the cochlea to move, vibrating the basilar membrane.
01:16Anatomy of the Ear
Auditory sensation, commonly called hearing, involves the transformation of sonic waves into neural impulses facilitated by the structures of the auditory organ. The prominent, flesh-like structure on the side of the head, called the auricle, directs sound waves towards the auditory canal. The auricle is often mislabeled as the pinna, a term more aligned with mobile structures like a feline's external ear. The auditory canal penetrates the cranium via the external auditory meatus of the...
01:22Hair Cells
Hair cells are the sensory receptors of the auditory system—they transduce mechanical sound waves into electrical energy that the nervous system can understand. Hair cells are located in the organ of Corti within the cochlea of the inner ear, between the basilar and tectorial membranes. The actual sensory receptors are called inner hair cells. The outer hair cells serve other functions, such as sound amplification in the cochlea, and are not discussed in detail here.
01:15Auditory Pathway
Auditory pathways constitute the complex neural circuits responsible for transmitting and interpreting auditory information from the peripheral auditory system to the brain. Sound waves are initially captured by the outer ear, funneled through the ear canal, and reach the tympanic membrane (eardrum). These vibrations are transmitted via the middle ear's ossicles to the inner ear's cochlea.
When viewed cross-sectionally, the cochlea reveals the scala vestibuli and scala tympani flanking the...
When viewed cross-sectionally, the cochlea reveals the scala vestibuli and scala tympani flanking the...
01:11The Auditory Ossicles
The auditory ossicles of the middle ear transmit sounds from the air as vibrations to the fluid-filled cochlea. The auditory ossicles consist of two malleus (hammer) bones, two incus (anvil) bones, and two stapes (stirrups), one on each side. These bones develop during the fetal stage and are the ones to ossify first. They are fully mature at birth and do not grow afterward.
The aptly named stapes look very much like a stirrup. The three ossicles are unique to mammals, and each plays a role in...
The aptly named stapes look very much like a stirrup. The three ossicles are unique to mammals, and each plays a role in...
01:54Convergent Evolution
Evolution shapes the features of organisms over time, ensuring that they are suited for the environments in which they live. Sometimes, selection pressure leads to the rise of similar but unrelated adaptations in organisms with no recent common ancestors, a process known as convergent evolution.The structures that arise from convergent evolution are called analogous structures. They are similar in function even if they are dissimilar in structure. Further, structures can be analogous while also...